The numbers came on top of weak German and euro-zone manufacturing activity data earlier in the day that had already exacerbated fears about a slowing global economy.

Pan-European stocks hit session lows after the US PMI data, with the STOXX 600 down 0.94 percent at 1359 GMT. Europe's banks index extended losses, down 2 percent and on track for their worst day since Feb. 7.

Ten-year British government bond yields dropped more than 4 basis points on the day to 1.021 percent, their lowest since September 2017, while the 2-year/10-year gilt yield curve was its flattest since August 2016 when the Bank of England launched a stimulus programme after the Brexit referendum.

Germany's 10-year bond yield fell to a new low of minus 0.023 percent, down over 5 bps on the day, tumbling as US bond yields fell.